1. Field of the Invention
The invention relates to assembly of manned space component modules and nodes from space travel vehicles into space stations. More specifically, the invention relates to structures for misalignment compensation during the final stages of docking (berthing) in the process of assembling such components into a multi-component space station, and thereafter due to thermal and other effects.
2. Background Art
The procedure whereby space components such as habitation modules, nodes and space vehicles are brought together and assembled to form a space station is referred to in the space industry as docking or berthing. The problem of misalignment in the final stages of that procedure is recognized and various attempts to correct for it have been devised.
Basically, an off axis or angular misalignment between components to be assembled in space is not easily corrected as would be the case for an assembly on the ground or between components with aerodynamic (airfoil) controls in the atmosphere. Accordingly, it is necessary that self-correcting means be provided so that alignment can be achieved on contact.
In the space component docking situation, the parallel mating of two interfacing surfaces is to be achieved so that clamping or otherwise securing of those surfaces can be accomplished.
One prior art concept involves the use of the standard universal joint (gimbal). That concept is very common and well known for coupling rotating elements which are not aligned perfectly, i.e., are not coaxial.
In the space situation, rotational coupling is not involved, rather an interface surface associated with one component (module, etc.) must be self aligning when contacted by another such surface associated with the component to be docked thereto as it approaches in the final stages of the docking procedure. The structure of the prior art gimbal includes two yokes and two pairs of short mutually orthogonal shafts as hinge points. The gimbal shafts and their bearings are all subjected to the very large shear forces resulting from pressurization of the modules and nodes assembled into a space station, particularly since the inter-module passages created by docking and securing are of substantial diameter. The result is that a high strength design is required, resulting in very substantial weight.
The state of the art in respect to flexible couplings and universal joints is mostly directed to the problem of rotating member couplings. Typical of that art are U.S. Pat. No. 1,414,411 to Herreshoff et al; U.S. Pat. No. 1,569,989 to Leipert; U.S. Pat. No. 1,605,356 to Leipert and U.S. Pat. No. 4,116,018 to Weible. While it may be said that any of those disclosures could be adapted to the space vehicle environment, none is readily adapted to the air-tight coupling required and none is well adapted to a practical combination including a bellows for pressure containment.
U.S. Pat. No. 4,556,182 to Bentall et al, discloses an arrangement including two mutually rotatable elements each having inclined plane faces such that rotation of one such element about a central axis causes an end face perpendicular to the central axis to assume a tilt variable over 360.degree. . The Bentall device is not adapted to assume an interface plane orientation upon axial contact as required by the space docking requirement.
A very important aspect of the requirement is that of resistance to the very large axial separation force caused by pressurization.
None of the aforementioned disclosures, nor the duct system flexible joint of U.S. Pat. No. 3,186,742 to Frankel et al affords that feature.